The present invention is related to brake apparatus having a "snow brake" function and particularly to such apparatus when associated with brake units having automatic slack adjusters.
Railroad vehicles operating in transit type service typically employ brake units similar to the type shown and disclosed in U.S. Pat. No. 3,707,208, in which an automatic, single-acting slack adjuster is employed to compensate for brake shoe/wheel tread wear. Operation of this slack adjuster mechanism is predicated upon movement of the brake apparatus to brake release position.
During winter conditions, the above-mentioned "snow brake" feature may be selectively activated by the train operator or attendant to automatically provide a light brake application during normal periods of brake release. In this way, friction generated by brake shoe/wheel tread engagement produces sufficient heat to prevent the accumulation of ice and snow between the brake shoe and wheel tread, without any significant braking action being realized.
In maintaining a light brake application in effect, however, the "snow brake" feature precludes movement of the brake apparatus to brake release position and accordingly renders the slack adjuster mechanism inoperative. It is therefore a requirement of the operator or train attendant to periodically (generally at the beginning of each day or each work shift) deactivate the "snow brake" and effect several cycles of brake applications and releases to allow operation of the slack adjuster mechanism to take up slack previously accumulated during activation of the "snow brake".